1. Field of the Invention
The present invention relates to a small size ink jet recording head and an ink jet recording head cartridge which are detachably mountable to a recording apparatus, and to a recording apparatus using the same.
2. Related Background Art
Recently, various recording systems have been developed. Among them, an ink jet recording system in which ink is ejected through ejection outlets in accordance with recording signal, is widely used because of the advantage of the small size and the low noise.
The recording head used in such an ink jet recording apparatus is in the form of a detachably mountable recording head cartridge from the standpoint of easy maintenance and service life or the like.
The recording head cartridge detachably mountable to the recording apparatus and the recording apparatus are electrically connected by electric connection contacts (connectors) for transmitting signals for driving the recording head from the recording apparatus. When the recording head is mounted on the recording apparatus, the contacts are electrically connected.
However, in the case of a detachably mountable recording head cartridge, there is a liability that the ink leaked through the ejection outlet contaminates the contacts with the result of insufficient electric connection.
In order to solve the problem, U.S. Pat. No. 4,635,080 discloses that the contacts are disposed on a surface which is different from an ejection side surface having the ejection outlets of a recording head cartridge having an integral ink container.
The recent demand for the small size of the recording apparatus requires a reduction in the size of the recording head cartridge. In this case, the ink capacity of an ink container constituting the recording head cartridge also decreases. In addition, there may be a difference in the service life of the ink container from that of the recording head which is also part of the head cartridge. Therefore, from the standpoint of cost and from the standpoint of re-use of the recording head, the recording head cartridge in which the ink container and the recording head are separable is considered.
The ink is supplied from the ink container to the recording head through an ink supply port. In addition, the driving signal is supplied by electric connections between the electric contacts of the recording head and the recording apparatus.
FIGS. 17 and 18 show an example of an ink jet recording head not using the present invention. The ink jet recording head is of a type in which electrothermal transducers are used as energy generating means, and ink droplets are ejected by bubble creation in the ink by the thermal energy produced by the electrothermal transducers. These figures show a recording head which is connectable to and separable from an ink container. A supporting plate 1 has a top surface to which an energy base plate and a wiring base plate 9 are bonded. The energy base plate (heater board) is made chiefly of Si or the like having on a surface thereof heat generating portions (heaters) of electrothermal transducers effective to generate thermal energy. The base plate 9 (Wiring board) is made chiefly of glass or epoxy resin material and is effective to transmit the electric signals from the main assembly of the recording apparatus to the heater board 2. The heater board 2 and the wiring board 9 are electrically connected together by wire bonding 7.
The top surface of the wiring board 9 is provided with contact pads (electric contacts) 4 electrically connected with a flexible wiring board of the main assembly of the recording apparatus.
The ink is supplied from an ink container or recording apparatus side through an ink supply member 6 to a common liquid chamber and ejection nozzles constituted by the bonding between the heater board 2 and a top plate 5, and the ink is ejected through the ejection outlets 8.
However, in such a recording head, an ink joint between an ink supply member 6 and an ink container or an ink supplying portion of the apparatus and a portion having the contact pads 4 of the wiring board 9 are disposed on the same side of the supporting plate 1. Therefore, when the recording head is connected or disengaged, the ink leaked from the ink joint may contact the contact pads with the result of insufficient or improper electric connection.
Recently, a further reduction in the size is desired. Since the number of pads and the area of each of the pads are more or less limited, it is difficult to further reduce the area occupied by the contact pads. In addition, the area of the recording head supporting plate is determined by the areas of the heater board portion, the wire bonding portion and the contact pad portion. For these reasons, further reduction in the size is not easy.
In order to solve such problems left to be solved, the inventors have previously proposed a recording head in which the disposition of an element substrate and a wiring substrate provided with energy generating means for generating energy available to discharge ink onto a support member is improved and a contact pad is formed on the side opposite to a surface on which the element substrate is disposed.
As a result of the inventor's further studies, it has been found that by improving the bending of the wiring substrate and the wiring thereof, the element substrate and the apparatus side can be electrically connected together by a more reliable and more positive method.